Known steering devices comprise a stationary steering wheel rim, a measurement transducer integrated into the steering wheel rim and provided for generating an electronic signal, and an actuator that can be actuated as a function of the electronic signal in order to adjust steerable wheels.
For some time now, due to reasons of both safety and convenience, more and more devices for actuating various vehicle functions are being arranged directly on the steering wheel so that the driver is no longer forced to take his/her hand off the steering wheel to operate such functions. The transmission of electric signals generated on a rotatable steering wheel to the actuating elements that are arranged in a stationary position on the car body, however, is not unproblematic, especially in case a large number of signals has to be transmitted. Therefore, stationary or virtually stationary steering devices have been proposed with which the mechanical coupling between the steering device and the steering linkage has been replaced by a measurement transducer on the steering device and by an actuator on the steering linkage. Such steering devices can dispense with the usual maximum of two-and-a-half to four revolutions of the steering wheel to reach the maximum wheel angle position, and the actual travel distance for the actuation of the steerable wheels can be limited to an angle of rotation of 30° or less. As a result, the transmission of a large number of signals no longer poses a problem since the actuation devices can be arranged on parts of the steering device that are configured so as to be stationary relative to the car body. This greatly simplifies the wiring layout needed to make an electrical connection between the actuation devices and the stationary parts.
A mechanical uncoupling and electric transmission of the steering command to the steerable wheels is also necessary if modern safety systems are to effectuate driver-independent vehicle stabilization and if an influence is to be exerted on the adjustment angle of the steerable wheels.
EP-A-1 046 572 describes a steering device with a non-rotatable frame that has an axis of symmetry and arc-shaped guide sections, a pair of handles that are coupled to each other and mounted on the guide sections so as to move in the same direction and that can be moved to a limited extent relative to the axis of symmetry, and it also describes a measurement transducer for generating an electric or electronic signal that serves to determine the position of the two handles relative to the frame.
WO-A 99/12791 relates to a steering device for a motor vehicle with an actuation member for initiating a steering movement and a steering linkage for transmitting the steering movement to the wheels, the actuation member consisting of a non-rotatable steering wheel the rim of which contains a band-shaped or chain-like actuation ring that is movable relative to the rim, and a measurement transducer for generating an electric or electronic position signal for the actuation ring. The steering linkage is actuated by an actuator that can be controlled by an electric or electronic regulating device as a function of the position signal.
DE 199 27 467 A1 describes a rotating steering wheel with touch elements for actuating electrically controllable devices in a motor vehicle, the touch elements being piezoelectric pressure sensors. Some of the pressure sensors are arranged in an activation area, whereas the other pressure sensors form a control area that is distinguished from the activation area. Through the actuation of the pressure sensors located in the activation area, it is intended to associate various control functions with the pressure sensors located in the control area.
JP-A 05-310130 discloses a steering wheel with pressure sensors detecting the pressure of the palms gripping the steering wheel. Through the level of the pressure exerted, it is intended to identify an imminent steering motion and to predict the direction of the steering motion.
The present invention provides a steering device that is less complex in design and that can consequently be manufactured more cost-effectively.